Question

I’ve solved one issue and ran into another. Basicaly i want to select question_id, answer and maximum number of occurences. I run my query from basic table that gathers questions and answers to them (question id represents question and answer represents answer from 0 to 5 that corresponds to other table but that doesn’t matter).

**survey_result**
question_id
answer (int from 0 to 5)

Sample survey_result:

question_id answer
1           3
1           5
1           2
2           2
2           0
2           4

Here’s the query, it’s purpose is to check for every single question, which answer (from 0 to 5) occured the most.

select question_id, answer, max(occurence_number) FROM
(select question_id, answer, count(*) as occurence_number
from survey_result
group by question_id, answer
order by question_id asc, occurence_number desc) as results
GROUP BY question_id

So a sub query results in something like this:

question_id answer occurence_number
1           0      12
1           1      20
1           2      34
1           3      5
1           4      9
1           5      15

But main query results something like this:

question_id answer occurence_number
1           0      12
2           0      20
3           0      34
4           0      5

So the problem is that it always shows answer 0, and i want to get correct answer number.

Answer 1

Sadly a bit redundant due to MySQL’s lack of a WITH statement, but this should do what you want. In case of a tie, it will return the higher answer.

SELECT s1.question_id, MAX(s1.answer) answer, MAX(s1.c) occurrences
FROM
   (SELECT question_id, answer, COUNT(*) c 
    FROM survey_result GROUP BY question_id,answer) s1
LEFT JOIN
   (SELECT question_id, answer, COUNT(*) c
    FROM survey_result GROUP BY question_id,answer) s2
  ON s1.question_id=s2.question_id
 AND s1.c < s2.c
WHERE s2.c IS NULL
GROUP BY question_id

An SQLfiddle to play with.